Flame resistant fabrics and garments having the appearance of denim

ABSTRACT

Disclosed are flame resistant fabrics and garments having the appearance of denim. In one embodiment, a piece-dyed, flame resistant fabric includes first flame resistant yarns that extend along the fabric in a first direction and second flame resistant yarns that extend along the fabric in a second that is different from the first direction so as to interweave the second flame resistant yarns with the first flame resistant yarns, wherein the first flame resistant yarns are dyed due to the piece dyeing and the second flame resistant yarns are substantially undyed to create the denim appearance.

BACKGROUND

Several occupations require an individual to be exposed to hazards such as flash fires or electrical arcs. To avoid being injured while working in such conditions, these individuals typically wear protective garments constructed of materials designed to protect them from heat and flame.

To cite an example, many utility and industrial workers wear denim garments. As referred to herein, “denim” is a twill fabric that is yarn dyed such that one yarn component (e.g., warp yarns) is dyed prior to constructing the fabric and the other yarn component (e.g., filling yarns) is not. It is the weaving of the dyed yarns with the undyed yarns that gives denim its distinctive appearance. Such denim is typically constructed of 100% cotton. Although not ideal from the standpoint of offering protection against flash fire and electrical arc hazards, many workers like the appearance and feel of cotton denim garments and believe that the protection they offer is adequate.

Unfortunately, a number of issues arise when cotton denim garments are used to protect against flash fires, electrical arcs, and other similar hazards. Although some protection is offered by such garments, better protection could be afforded by garments composed of flame resistant fabrics. Although it is possible to treat cotton denim fabric in order to increase its flame resistance, this flame resistance may degrade over the life of the fabric through physical wear and laundering. Aside from issues concerning flame resistance, yarn dyeing processes used to create known denim fabrics are relatively expensive as compared to piece-dyeing processes, and therefore increase the overall cost of producing a garment.

SUMMARY

Disclosed are flame resistant fabrics and garments having the appearance of denim. In one embodiment, a piece-dyed, flame resistant fabric includes first flame resistant yarns that extend along the fabric in a first direction and second flame resistant yarns that extend along the fabric in a second that is different from the first direction so as to interweave the second flame resistant yarns with the first flame resistant yarns, wherein the first flame resistant yarns are dyed due to the piece dyeing but the second flame resistant yarns are substantially undyed to create the denim appearance.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed fabrics and methods can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale.

FIG. 1 is a front view of an embodiment of a protective garment.

FIG. 2 is a schematic representation of an embodiment of a fabric that can be used to construct the garment shown in FIG. 1.

FIG. 3 is a flow diagram illustrating an embodiment of a method that can be used to dye the fabric shown in FIG. 2.

DETAILED DESCRIPTION

FIG. 1 illustrates an example protective garment 100. More particularly, FIG. 1 illustrates a pair of pants that can be worn by utility and industrial personnel to protect against flash fire hazards, electric arc hazards, etc. It is noted that, although a pair of pants is shown in the figure and described herein, the present disclosure more generally pertains to protective garments, as well as the fabrics used to construct them. Accordingly, other garments can be constructed including, for example, jackets, shirts, overalls, etc. All such garments are intended to fall within the scope of the present disclosure.

FIG. 2 is a schematic view of an example fabric 200 that can be used to construct the protective garment 100 shown in FIG. 1. As indicated in FIG. 2, the fabric 200 can be constructed as a plain weave fabric that comprises a plurality of warp yarns 202 and a plurality of filling yarns 204 that together form the body of the fabric 200. Although a plain weave is depicted in FIG. 2, other configurations could be used such as, for example, a twill. Preferably, the warp yarns 202 and filling yarns 204 are both constructed of flame resistant material. Regardless, however, the warp yarns 202 and filling yarns 204 are selected such that either the warp yarns 202 or filling yarns 204 are dyed using a piece-dyeing process while the other yarns remain substantially undyed so as to provide the appearance of denim. The process of dyeing the fabric 200 in this manner is discussed in greater detail below. For ease of description, it is assumed that the warp yarns 202 are dyed while the filling yarns 204 remain substantially undyed. Note, however, that the filling yarns 204 could be dyed and the warp yarns 202 left substantially undyed by merely reversing the selection of materials for the warp yarns 202 and the filling yarns 204. Therefore, the fabric 200 may more generally be described as comprising first yarns that extend along the fabric in a first direction and that are dyed, and second yarns that extend along the fabric in a second that is different from the first direction so as to interweave the first yarns and that are substantially undyed.

In some embodiments, the warp yarns 202 comprise a blend of inherently flame resistant fibers and another type of fiber, such as a flame resistant (FR) cellulosic fiber (i.e., a fiber that is not naturally flame resistant, but which can be made so through appropriate treatment). For example, a para-aramid/FR rayon blend or a meta-aramid/FR rayon blend may be used. In other embodiments, the warp yarns 202 comprise a blend of modacrylic and FR rayon. In cases in which an aramid blend is used, a para-aramid (e.g., Kevlar® or Twaron®)/FR rayon blend and/or a non-crystalline meta-aramid (e.g., Nomex® type 462)/FR rayon blend may be used. As is known in the art, Kevlar® and Twaron® fibers are composed of 100% para-aramid while Nomex® type 462 fibers are composed of 93% non-crystalline meta-aramid. Although para-aramid can be difficult to dye, suitable dyeing of a blended yarn may be achievable, for instance by only or primarily dyeing the non-para-aramid component(s). Other FR cellulosics that could be used include FR cotton, FR acetate, FR triacetate, and FR lyocell.

In some embodiments, the filling yarns 204 are composed of inherently flame resistant material that resists the employed dyeing process and therefore remains substantially undyed (i.e., substantially uncolored) after the piece-dyeing process used to dye the warp yarns 202 is completed. In one embodiment, the filling yarns 204 comprise an aramid material that resists dyeing such as crystalline meta-aramid (e.g., Nomex® type 450). In another embodiment, the filling yarns 204 comprise 100% para-aramid fibers (e.g., Kevlar® or Twaron®). As is known in the art, Nomex® type 450 fibers are composed of 100% crystalline meta-aramid, which is relatively difficult to dye. Typically, the resultant fabric has a weight ranging from approximately 4 ounces per square yard (osy) to approximately 15 osy.

The dyeing techniques and dyes used to achieve a flame resistant fabric having the appearance of denim depend upon the materials selected for the warp yarns 202 and the filling yarns 204 and the desired result in terms of which component (warp or filling) is dyed and which is not. In some embodiments, the dyeing techniques used comprise low temperature (i.e., less than the boiling temperature) dyeing with or without a dye-assistant (or “carrier”). Example dyeing methods are described in U.S. Pat. No. 6,547,835, which is hereby incorporated by reference. In that particular dyes cannot be used to dye some materials and some materials can only be dyed by certain dyes if a dye-assistant is used, it can be appreciated that the desired result, whether it be dyed warp yarns and undyed filling yarns or undyed warp yarns and dyed filling yarns, can be achieved by varying one or more of the materials used, dyes used, and dye-assistant used (if any). Example dyes include direct/disperse, fiber reactive/disperse, direct/basic, fiber reactive/basic, direct, fiber reactive, vat, and sulfur dyes, and may be, for instance, blue or black (i.e., popular colors for denim garments).

Example fabrics and dyeing techniques are identified in Table I that result in dyed warp yarns and substantially undyed filling yarns, which yields a flame resistant fabric having the appearance of denim. However, as noted above, the same effect can be achieved if the filling yarns 204 are dyed and the warp yarns 204 remain substantially undyed. TABLE I Warp Materials Filling Materials Dyeing Technique Dye Type 60/40 FR rayon/Kevlar ® Nomex ® type 450 low temperature, no dye- direct/disperse assistant 60/40 FR rayon/Kevlar ® Nomex ® type 450 low temperature, no dye- fiber assistant reactive/disperse 60/40 FR rayon/Kevlar ® Nomex ® type 450 low temperature, dye- direct/disperse assistant 60/40 FR rayon/Kevlar ® Nomex ® type 450 low temperature, dye- fiber assistant reactive/disperse 65/35 Nomex ® type Nomex ® type 450 low temperature, no dye- direct/basic 462/FR rayon assistant 65/35 Nomex ® type Nomex ® type 450 low temperature, no dye- fiber reactive/basic 462/FR rayon assistant 65/35 Nomex ® type Nomex ® type 450 low temperature, dye- direct/basic 462/FR rayon assistant 65/35 Nomex ® type Nomex ® type 450 low temperature, dye- fiber reactive/basic 462/FR rayon assistant 50/50 FR Nomex ® type 450 low temperature, no dye- direct/basic rayon/modacrylic assistant 50/50 FR Nomex ® type 450 low temperature, no dye- fiber reactive/basic rayon/modacrylic assistant FR rayon Nomex ® type 450 low temperature, no dye- direct assistant FR rayon Nomex ® type 450 low temperature, no dye- fiber reactive assistant FR rayon Nomex ® type 450 low temperature, no dye- vat assistant FR rayon Nomex ® type 450 low temperature, no dye- sulfur assistant

FIG. 3 is a flow chart that illustrates an example method for piece dyeing fabric so as to achieve a flame resistant garment having the appearance of denim. The first step, as shown in block 300, comprises contacting a flame resistant fabric (which includes the warp yarns and filling yarns) with a dye bath including a dye and, optionally, a dye-assistant. The dye bath may include one or more of, for example, direct/disperse, fiber reactive/disperse, direct/basic, fiber reactive/basic, direct, fiber reactive, vat, and sulfur dyes. When a dye-assistant is used in the dye bath, the dye-assistant may include one or more of, for example, N-cyclohexylpyrrolidone, benzyl alcohol, N,N-dibutylformamide, N,N-diethylbenzamide, hexadecyltrimethyl ammonium salt, N,N-dimethylbenzamide, N,N-diethyl-m-toluamide, N-octylpyrrolidone, aryl ether, Halcomid M-8/10 (an approximately 50/50 blend of N,N-dimethylcaprylamide and N,N-dimethylcapramide), and mixtures thereof. Next, as shown in block 302, the flame resistant fabric is dyed at a peak temperature that does not exceed the boiling temperature (e.g., 190° F.), to fix the dye within one yarn component (e.g., the warp yarns 202) but not, at least to a significant degree, the other yarn component (e.g., the filling yarns 204).

At this point, the fabric (once rinsed and dried) will have the appearance of conventional denim, but will further have a relatively durable flame resistance. Accordingly, the fabric is suitable for replacement of cotton denim in garments used by those who encounter heat and flame hazards. 

1. A piece-dyed, flame resistant fabric having the appearance of denim, the fabric comprising: first flame resistant yarns that extend along the fabric in a first direction; and second flame resistant yarns that extend along the fabric in a second that is different from the first direction so as to interweave the second flame resistant yarns with the first flame resistant yarns; wherein the first flame resistant yarns are dyed due to the piece dyeing but the second flame resistant yarns are substantially undyed to create the denim appearance.
 2. The fabric of claim 1, wherein the first flame resistant yarns are warp yarns.
 3. The fabric of claim 1, wherein the first flame resistant yarns comprise inherently flame resistant material.
 4. The fabric of claim 3, wherein the first flame resistant yarns comprise at least one of para-aramid fibers and uncrystallized meta-aramid fibers.
 5. The fabric of claim 3, wherein the first flame resistant yarns comprise modacrylic fibers.
 6. The fabric of claim 1, wherein the first flame resistant yarns comprise flame resistant cellulosic fibers.
 7. The fabric of claim 1, wherein the first flame resistant yarns are dyed one of blue and black.
 8. The fabric of claim 1, wherein the second flame resistant yarns are filling yarns.
 9. The fabric of claim 1, wherein the second flame resistant yarns comprise inherently flame resistant material.
 10. The fabric of claim 9, wherein the second flame resistant yarns comprise at least one of para-aramid fibers and crystallized meta-aramid fibers.
 11. The fabric of claim 1, wherein the second flame resistant yarns resist dyeing such that the first flame resistant yarns can be dyed without dyeing the second flame resistant yarns in a piece-dyeing process.
 12. The fabric of claim 1, wherein the fabric is a plain weave.
 13. The fabric of claim 1, wherein the fabric is a twill.
 14. The fabric of claim 1, wherein the fabric has a weight ranging from approximately 4 to 15 ounces per square yard.
 15. A piece-dyed, flame resistant fabric, comprising: flame resistant warp yarns; and flame resistant filling yarns; wherein the warp yarns are dyed due to the piece dyeing, but the second flame resistant yarns are not dyed despite the piece dyeing.
 16. The fabric of claim 15, wherein the warp yarns comprise at least one of aramid fibers and modacrylic fibers.
 17. The fabric of claim 16, wherein the warp yarns further comprise flame resistant cellulosic yarns.
 18. The fabric of claim 15, wherein the warp yarns are dyed one of blue and black.
 19. The fabric of claim 15, wherein the filling yarns comprise at least one of para-aramid fibers and crystallized meta-aramid fibers.
 20. The fabric of claim 15, wherein the fabric is one of a plain weave and a twill.
 21. The fabric of claim 15, wherein the fabric has a weight ranging from approximately 4 to 15 ounces per square yard.
 22. A protective garment composed of a piece-dyed fabric, comprising: first flame resistant yarns that extend along the fabric in a first direction; and second flame resistant yarns that extend along the fabric in a second that is different from the first direction so as to interweave with the first flame resistant yarns; wherein the first flame resistant yarns are dyed due to the piece dyeing and the second flame resistant yarns are substantially undyed to create an appearance of denim for the fabric and the garment.
 23. The garment of claim 22, wherein the first flame resistant yarns are warp yarns and the second flame resistant yarns are filling yarns.
 24. The garment of claim 22, wherein the first flame resistant yarns comprise at least one of para-aramid fibers, uncrystallized meta-aramid fibers, modacrylic fibers, and flame resistant cellulosic fibers.
 25. The garment of claim 22, wherein the second flame resistant yarns comprise at least one of para-aramid fibers and crystallized meta-aramid fibers.
 26. The garment of claim 22, wherein the garment fabric is one of a plain weave and a twill.
 27. The garment of claim 22, wherein the garment fabric has a weight ranging from approximately 4 to 15 ounces per square yard.
 28. The garment of claim 22, wherein the garment comprises one of a jacket, a shirt, pants, and overalls.
 29. A method for dyeing a flame resistant fabric, the method comprising: contacting a flame resistant fabric comprising flame resistant yarns extending in first and second directions along the fabric so as to interweave with a dye bath; and heating the dye bath such that dye is fixed within the flame resistant yarns extending in the first direction but not in the flame resistant yarns extending in the second direction so as to create the appearance of denim.
 30. The method of claim 29, wherein contacting a flame resistant fabric comprises piece dyeing a fabric that includes warp yarns that accept dyeing and filling yarns that resist dyeing.
 31. The method of claim 29, wherein contacting a flame resistant fabric comprises piece dyeing a fabric that includes warp yarns that resist dyeing and filling yarns that accept dyeing.
 32. The method of claim 29, wherein contacting a flame resistant fabric comprises piece dyeing a flame resistant fabric including first yarns and second yarns that interweave the first yarns, the first yarns comprising at least one of aramid fibers, modacrylic fibers, and flame resistant cellulosic fibers, the second yarns comprising at least one of para-aramid fibers and crystallized meta-aramid fibers.
 33. The method of claim 29, wherein contacting a flame resistant fabric with a dye bath comprises contacting the fabric with a dye bath comprising a dye selected from the group consisting of a direct/disperse dye, a fiber reactive/disperse dye, a direct/basic dye, a fiber reactive/basic dye, a direct dye, a fiber reactive dye, a vat dye, a sulfur dye, and mixtures thereof.
 34. The method of claim 29, wherein contacting a flame resistant fabric with a dye bath comprises contacting the fabric with a dye bath comprising a dye-assistant selected from the group consisting of N-cyclohexylpyrrolidone, benzyl alcohol, N,N-dibutylformamide, N,N-diethylbenzamide, hexadecyltrimethyl ammonium salt, N,N-dimethylbenzamide, N,N-diethyl-m-toluamide, N-octylpyrrolidone, aryl ether, Halcomid M-8/10 (an approximately 50/50 blend of N,N-dimethylcaprylamide and N,N-dimethylcapramide), and mixtures thereof.
 35. The method of claim 29, wherein heating the dye bath comprises heating the dye bath to a peak temperature that does not exceed 190° F. 